Re: Without enough forests, pandas will be starving.
I would choose the first version. In a serious context, "starve" in continuous forms can convey the meaning "starve to death", e.g.
1. People in Africa are starving.
But "starve" (again, in continuous forms) can also convey "be very hungry", in an exaggerated, non-serious way, e.g.
2. I'm starving = I'm very hungry
3. I was starving = I was very hungry
This is less true of the continuous future; but the "very hungry" meaning does seem to interfere with your intended meaning, in your example #2.
Not a professional ESL teacher.